M2L8: Gene editing in humans

Now, in the last lecture, we saw that gene editing can be used to add some genes and silence some of them. But in all the cases, we studied how gene editing is done in plants

Now we go one step ahead. We will study if the same can be done in humans or not?

It has been found that maximum number of hereditary disorders in Indians, can be attributed to the following diseases

Cystic Fibrosis	Abnormal pancreatic functions & generally leads to early death
Down Syndrome	Also called Mongolism. Chromosome 21 occurs in triplicate (trisomy) rather than duplicate. Affected individuals carry 47 chromosomes are greatly retard mentally & physically.
Hemophilia	Sex linked gene. Results in excessive bleeding
Huntington’s Disease	Caused by dominant autosomal gene which leads to progressive deterioration of the nervous system. Develops at an age of 30 to 40 years causing loss of control of limbs.
Muscular Dystrophy	Sex linked recessive disease developing during 1-6 years.  Patient becomes confined to wheel chair by 12 year of age. People die before 20.
Sickle Cell Anemia	Caused by abnormal hemoglobin molecule due to recessive gene in homozygous condition resulting in sickling of RBCs.
Tay Sachs Disease	Caused by autosomal recessive gene.  Leads to progressive mental degradation resulting in death by the age of 2-3 years.
Thalassemia (Cooley’s Anaemia).	Occurs mostly in children & is nearly fatal. Controlled by a recessive gene which causes severe anemia.

Can we do gene editing here, to treat these genetical disorders?

Answer is yes. Today we have CRISPR

“CRISPR” (pronounced “crisper”) stands for Clustered Regularly Interspaced Short Palindromic Repeats, which are the hallmark of a bacterial defense system that forms the basis for CRISPR-Cas9 genome editing technology. CRISPR-Cas9 is proving to be an efficient and customizable alternative to other existing genome editing tools. Since the CRISPR-Cas9 system itself is capable of cutting DNA strands, CRISPRs do not need to be paired with separate cleaving enzymes as other tools do. They can also easily be matched with tailor-made “guide” RNA (gRNA) sequences designed to lead them to their DNA targets. Tens of thousands of such gRNA sequences have already been created and are available to the research community. CRISPR-Cas9 can also be used to target multiple genes simultaneously, which is another advantage that sets it apart from other gene-editing tools.

Pros

·         It will help to treat genetical disorders that are inherited from generation to generation.

·         Will help to build climate resilient crops

·         Will help to make new medicines and vaccines

Medical issue

Till date, we were considering genes in isolation. However, it has been found that genes behave as a family. Hence, interfering in the DNA ribbon by swapping it with a foreign gene leads to an erratic behavior among other genes causing a new form of diabetes or Cancer. Thus, treatment of one disease is opening the gates for one new disease. To prevent this, a detailed transcriptome analysis should be done before hand. What if the unborn child, opposes the action of his parents/guardians and claims it to be an exploitation, because he was helpless at that time?

Moral issues related to CRISPR

UK government is planning to allow doctors to use this technique. But some MPs are against this method citing this is also stem-cell research. You are ‘playing God’ and interfering with his creation and hence against the (Christianity) religion.

Ethical issue

This research will lead to “Designer babies” for example, pick DNA of Sachin for Stamina, DNA of Bacchan for Height, Hrithik Roshan for his eyes and thus assemble an embryo like assembling a mobile phone. Since this follows all the major rules, that are supposed to be followed before patenting like commercial utility, innovation and invention, can designer babies be commercialized like we have done to other life organisms like Glofish and Bt Brinjal?

Social issue

Designer babies are bad because then society will be divided into two parts: those with superior looks-body thanks to genetically engineering vs. those normally born. Hitler was also trying similar thing: remove all the Jews, handicapped and gypsies and create the strong Aryan race with pure genes.

Legal issue

DNA profiling and editing using CRISPR, can be used to claim statistical evidence that could affect employment or insurance or the ability to obtain financial services for the participant (chances of discrimination)

So, with this technology, should we allow the doctors to design a new baby? A completely customized one? I will leave that answer on you.